I used to hear that joke, but the punchline was "American". When I moved to the UK, the punchline was "British". Now I hear it again for the French.

Interestingly, it's doubtful that this punchline would be "Dutch" or "German". There are many countries for which this simply wouldn't be meaningful, but it's nice to know that Americans aren't alone in this.

Nothing wrong with being monolingual; my mother is monolingual

Thinking back, I'm not sure if I ever met anyone French, American, or British who did not speak at least two languages. (In most cases, the second being Norwegian, though there was this French woman whose second language was English.) But I'm pretty sure I've met Germans who appeared to comprehend no other language.